The Marshal of the Sejm (Polish: Marszałek Sejmu, pronounced [marˈʂawɛk ˈsɛjmu]) is the speaker (chair) of the Sejm, the lower house of the Polish Parliament.

In the Kingdom of Galicia and Lodomeria, from 1861, the chairman of the Provincial Sejm of Galicia with its seat at Lwów bore the title Marszałek krajowy (Province Marshal).

The Kingdom of Poland, from 1916 to 1918, used the title Marszałek Rady Stanu (Marshal of the State Council).

Until 1935 (when superseded by the Senate Marshal), the Marshal or Chairman of the Sejm substituted for the President of Poland in the latter's absence or disability (Acting President of the Republic of Poland).

He (or she) appoints the Chief of the Chambers (of the Sejm, and of the Senat), and since 1989 substitutes for the President of Poland in the event of that office's vacancy.